Field of the Invention
The invention relates to a polyaxial bone anchoring device with an enlarged pivot angle. The bone anchoring device includes a bone anchoring element for anchoring in a bone or a vertebra, and a receiving part for coupling the bone anchoring element to a stabilization element such as a spinal rod, where the bone anchoring element is pivotable in the receiving part and can be pivoted out of a central axis with an enlarged pivot angle. The orientation of the enlarged pivot angle may be selectable within a range of 360° around the central axis and may be automatically achieved by pivoting the receiving part relative to the bone anchoring element.
Description of Related Art
A polyaxial bone anchoring device with an enlarged pivot angle is described in U.S. Pat. No. 6,736,820. This bone anchoring device includes a bone screw and a receiving part with a seat for the head of the bone screw. In order that the screw member can be pivoted to at least one side by an enlarged angle, the edge bounding the free of the receiving part is of asymmetric construction. In a modified embodiment, an insert piece is provided, which has a spherical bottom as a seat for the head of the screw member.
US 2007/0118123 A1 describes a polyaxial bone anchor with increased angulation. The polyaxial bone anchor has a locking element shaped and configured to allow an anchoring member e.g. a screw or hook to polyaxially rotate at large angles about a central axis of the bone anchor before compression locking the anchoring member within an anchor head.